compared to true 1080p footage. you got some reading to do:
the mkIII is very soft even among other DSLRs. removing the OLP helps a little but still trails in detail and definitively doesn't deliver anywhere close to the quality of true 1080p. Sorry but for 3500 dollars, it should do better.
I've read every single article on EOSHD, I've used the FS100, C300, played with the Scarlett, and sure the 5DIII may not resolve true 1080p but I still think the footage looks great. Yes it could look better, but I wouldn't call it "poor" ever. This is an example of what I would consider "poor quality": http://www.youtube.com/watch?v=0yUi1SVPHwQ#
So sorry, I just can't put the 5DIII in the poor quality category, sure maybe "fair," "decent," or "not quite 1080p" category would be appropriate, but "poor?" Come on. 5DIII is better than 5DII, which would make the 5DII terribly poor, but if that was the case then no one would have ever noticed it and the DSLR revolution never would have happen, but as I remember that's not quite how things went down.
And no one that watches the stuff I do is counting lines of resolution, they all think it looks amazing. You have to remember your audience usually isn't a bunch of pixel-peepers, and 99% of the time they just can't tell the difference. I still think it's a great camera for $3500, and the stills features more than make up for it's shortcomings on the video side.
I have to ask, what exactly are you shooting that the 5DIII would ruin the quality of the content/story? The 5DII has been used on House, 24, commercials, award-winning movies, etc. James Cameron used it for personal projects, yet somehow it's not good enough for you? Content is king, and if a couple hundred lines of resolution are enough to ruin your project you probably have no business shooting video in the first place. At this stage it doesn't matter, you should be able to make an awesome movie with a 5DII or 5DIII, but I guess it's easier to tell yourself "if only I had an Alexa, then I could make the greatest movie ever!"